Demountable shelter



6 Sheets-Sheet 1 Filed NOV. 21, 1958 IIIV.

INVENTOR. l/iuava' 5 A/lCWOLf'O/V ,4 TTOENEVJ' y 23, 1963 L. E.NICHOLSON 3,091,002

DEMOUNTABLE SHELTER Filed NOV. 21, 1958 6 Sheets-Sheet 2 ,4 rroe/va fMay 2 1963 L. E. NICHOLSON DEMOUNTABLE SHELTER 6 Sheets-Sheet 3 FiledNov. 21, 1958 0 EM m5 a N E W M A rive/V576 y 28, 1963 L. E. NICHOLSON3,091,002

DEMOUNTABLE SHELTER Filed Nov. 21, 1958 6 Sheets-Sheet 4 ,4 rrae/va a y1963 L. E. NICHOLSON 3,091,002

DEMOUNTABLE SHELTER Filed Nov. 21, 1958 6 Sheets-Sheet 5 f7 INVENTOR.

@M MZM y 1963 L. E. NICHOLSON 3,091,002

DEMOUNTABLE SHELTER Filed Nov. 21, 1958 6 Sheets-Sheet 6 3,091,002UEMGUNTABLE SHELTER Laurence E. Nicholson, 404 2nd St, Anacortes, Wash.Filed Nov. 21, 1958, Ser. No. 775,413 8 Elms. (Cl. 202) The shelter ofthe present invention is intended primarily for temporary use and hasspecial utility for protecting from the weather articles or materials tobe stored, or may be used as a workshop such as during the constructionof a building of permanent type.

A principal object of the present invention is to provide a shelterstructure which is light and made of a minimum quantity of economicalmaterials while being strong and rigid.

To facilitate temporary use of the shelter, it can be erected or set upeasily and quickly without special tools and can be knocked down againwith equal facility.

The components of the shelter can be assembled and held in assembledcondition without being connected by fastening devices such as nails,screws, clips or the like, although the shelter is fabricated from alarge number of small components. The variety of such components is keptto a minimum, however, and they can be assembled in differentrelationships to provide shelters of different shapes. Moreover,components of the same type can be made in different sizes and thenumber of components utilized can be varied to construct shelters ofdilferent size. When disassembled, the components can be storedcompactly.

A shelter structure having these advantages can be constructed from amultiplicity of wood stringer and rib spreader components. Eachprincipal component includes at least one stringer and a plurality ofrib spreaders which are collapsible for storage, such as the spreadersbeing swiveled on the stringers. For shelters of considerable length,connector components may be utilized to bridge between adjacentstringers. The assembled components can be bound together to form arigid frame which can be covered by a skin of either stiff or limp sheetmaterial.

FIGURE 1 is a view showing components in relation ship to be assembledbut still disengaged, and FIGURE 2 is a similar view showing suchcomponents interengaged.

FIGURE 3 is a fragmentary vertical sectional view through an assembledshelter.

FIGURE 4 is a fragmentary inside elevation of an end portion of such ashelter, and FIGURE 5 is an enlarged vertical section taken on line 5-5of FIGURE 4.

FIGURE 6 is a fragmentary elevation view of an alternate type of shelterframe structure.

FIGURE 7 is a fragmentary exterior elevation of a modified form ofshelter, and FIGURE 8 is a sectional view on line 88 of FIGURE 7.

FIGURE 9 is a top perspective view of portions of components showninterengaged with parts broken away.

FIGURE 10 is an end view of components assembled in the relationshipshown in FIGURE 9, and FIGURE 11 is a similar view showing an alternateassembly of such components.

FIGURE 12 is a top perspective view of an end portion of a stringercomponent in collapsed condition, and FIGURE 13 is a similar view ofsuch a component, in expanded condition.

FIGURE 14 is a top perspective view of a connector component with partsbroken away.

FIGURE 15 is a top perspective view of an end portion of a stringercomponent in expanded condition engaged with an end portion of aconnector component, parts being broken away.

FIGURE 16 is a top perspective view of an end portion of another type ofstringer component in expanded condi- 3,091,902 Patented May 28, 1963tion, and FIGURE 17 is a similar view of such component collapsed.

FIGURE 18 is a top perspective view of end portions of assembledstringer components of the FIGURE 16 type, and FIGURE 19 is a verticalsectional view through such assembly.

FIGURE 20 is a vertical sectional view through stringer components ofthe FIGURE 16 type assembled in a relationship difierent from that ofFIGURE 18.

FIGURE 21 is an edge view of a foldable stringer component in unfoldedcondition, FIGURE 22 is a similar view of such component partiallyfolded, and FIGURE 23 is a similar View of such component fully folded.

FIGURE 24 is a side view of a portion of the stringer component ofFIGURE 21 from line 24-24 of FIG- URE 21.

FIGURE 25 is a top perspective view of a folding joint shown in FIGURE24, and FIGURE 26 is a sectional View through the joint on line 2626 ofFIGURE 25.

FIGURE 27 is an edge view of a different type of stringer componentshown in unfolded condition, and FIGURE 28 is a similar view of suchcomponent folded.

FIGURE 29 is a side view of a portion of the component of FIGURE 27 inunfolded condition, and FIG- URE 30 is a sectional view through aportion of such component taken on line 30-30 of FIGURE 29. FIG- URE 31is a top perspective view of a foldable joint in such a component.

FIGURE 32 is a top perspective view of an end portion of an alternativetype of stringer component with parts broken away, shown expanded in onemanner, and FIGURE 33 is a similar view of the same component expandedin a different manner. FIGURE 34 is a transverse section through suchcomponents expanded in the manner illustrated in FIGURE 32 and showninterengaged, and FIGURE 35 is a similar view showing a multiplicity ofsuch components assembled. FIGURE 36 is a transverse sectional viewthrough such components expanded in the manner illustrated in FIGURE 33,and shown interengaged, and FIGURE 37 is a similar view showing amultiplicity of such components interengaged.

FIGURE 38 is a fragmentary elevation of modified components assembled.

FIGURE 39 is a view of further modified stringer component's ready forassembly. FIGURE 40 is a fragmentary perspective view of portions ofsuch components in adjacent relationship, and FIGURE 41 is a similarview of the same parts of such components assembled. FIGURE 42 is a topperspective view of a joint between such components.

Especially in connection with construction work, it frequently isdesirable to protect from the weather lumber and other buildingmaterials. In some instances, it is desirable to provide an areaprotected from the weather for processing such materials, such as forcutting steel and lumber and perhaps fabricating building elements bywelding or laminating. Also, shelters of temporary character arefrequently useful for covering vehicles such as automobiles and boatsduring storage, or While building a boat, for example. Temporaryshelters are also useful for actually housing construction crews,especially during the summer. Shelters embodying the present inventionmay be used either as temporary shelters or for extended periods.

The shelter of the present invent-ion has a curved roof which preferablyis curved substantially semi-cylindrically and may be of any length. Thedegree of roof curvature and the width of the building are governedprincipally by the particular design of the individual rib componentsbecause each component will span a predetermined angle.

. The formation of the rib section will determine the size of such angleand the length of the chord over which such a 'angleis turned.Inthe-iollowing description, representative angles of 15 and 10 betweenstringers have been selected for purposes of illustration, but it willbe understood that such anglesniay be increased or decreased by alteringthe design of the building components.

The shelter is fabricated from three principal types of structure:first, "a frame composed of stringer components including rib spreaderelements which'can be assembled in interfitting relationship and mayinclude connector stringer components; second, tying structure tointegrate the stringer components in assembled condition, into a unitaryshelter frame; and'third, a skin of sheet material coverin'g'the framewhich may be either transparent,translucent or opaque, continuousor insecsens, of 'stifi' material or limp material, and, if of stiffmaterial, may be smooth or corrugated. 'Also, a wide variety ofmaterials can be used such as cloth, plastic or metal.

Wnile the stringer components forming the frame also can be made ofmetal, plastic or other materials, it is preferred for the sake ofeconomy to use wood. The strength and weight of wood is quitesatisfactory torshelters of reasonable size. component is shown inFIGURES 12 and 13 as including a stringer formed by parallel stringerstripelements '1 and 2 interconnected in spacedparallel relationship byfiller blocks 3 secured between them at intervals along their length.Rib spreaders 4 are carried by the stringer extending transversely ofthe length of the stringer and spaced lengthwise of it. Such Spreadersare of a width to be received between the stringer strips 1 and'2, It ispreferred that the'stringer components be collapsible, for which purposerib spreaders are mounted by pivots 5 for swiveling between thecollapsed position shown in FIGURE 12, in which the spreaders aredisposed substantially coplanar with the stringer strips 1 and 2, andthe expanded condition of FIGURE 13, in which the rib spreaders aredisposed 'tranversely of the stringer strip elements '1 and 2 so thattheir end portions project equidistantly beyond opposite sides ofthe'stringer elements. The intervals between the fillerblocks 3preferably are sufiicient-lygreat to accommodate rib spreaders 4disposed lengthwise between the filler blocks.

, The length of the spreaders 4 determines" the spacing between thestringers when the stringer components are assembled. When adjacentstringer components are assembled in side-iby-siderelationship, asshownin FIG- URES 2 and 9, the end por'tionsof rib spreaders of adjacentcomponents will overlap. Consequently,the spacing of the stringers willbe approx-imately 'one half of'the length of "the spreaders 4, and the"width of a conipo'site rib measured lengthwise of the stringers will betwice the thickness:of aspreader*4. Such arrangement provides quite a'strong and rigid frame structure;

It is,"of course, necessary to interenga'ge elements of adjacentcomponents *whenthey are assembled so as 'to transmit stresses from onecomponent to the next component lengthwise of the spreaderswhen they arein expanded condition. To provide proper fitting of the 'spreadersotadjacent components, the opposite end portions of eachspreaderare'tapered, each spreader having Y an edge with end portions inclinedoppositely from the central portionof such spreader edge over the majorportion'ofthespreader length, One edge of thespreader *niayIbe'perpendioular 'to 'a central plane through the stringer carryingsuch spreader and the opposite edge portiomfiiwi-ll 'b eatanangle"greater than 90 to such plane. 'In forming such taper 'or edgeincline, consideration shoirld'be' given to the angular'displacetrr'entdesired between "the central planes'of adjacent'components. In order'toenable the inclined'edges'of the rib spreaders to be disposedcoplanar when the components are assembled as shown in FIGURE 9, theanglebet-ween the central radial plane through. the stringer rand theinclined edge 6 of the end portion of the rib spreader extending Apreferred type of stringer transversely of the stringer *will be minusone-half of the angle between the central radial planes throughstringers of adjacent components when measured from the inner side ofthe components, and 90 plus one-half of the angle between such planes ofadjacent components when measured at the outer side of the components.Stated inanother way, the an'gle between the pivot axis 5 and eachinclined edge-'6 of the end portion of a rib spreader in expandedcondition will be 99 plus one-half of the angle between the"pivots"5 ofadjacent interengaged components. a

In the particular examples'hown in FIGURE 9, the angle between thecentral radial planes through adjacent stringer components and betweenthe pivots 5 of adjacent components is shown in FIGURE 10 as being 15.Consequently, the exterior angle'between a central nadial stringer planeor a pivot axis and the outer inclined edge 6 of the rib spreader, whenmeasured at the outside of the shelter, will be 90 plus one-half 'of'15, "making 97 /2 The surface of the stringer strip 2 facing thestringer strip 1 is perpendicular to the axes of pivots 5 if the strips2 are of rectangular cross section as is preferred. If the ends of ribspreaders of adjacent stringer components are to underlap the stringerstrips 2, therefore, and bear evenly against'their undersides, the tipsof the rib spreaders must have chamfered corners 7.' The included anglebetween the spreader edge portions 6 and 7 will be 180 minus one-half ofthe angle between the pivots 5 of adjacent components which, in theillustration given, will be 180 minus 7 /2", or 172 /2". When adjacentstringer components in expanded condition are assembled as shown inFlGURES 9 and 10, therefore, the edges of the overlapping spreader endportions will be in registry so that the surfaces 6 of adjacentspreaders will be coplanar and the chamfered corner surface! of eachspreader will be coplanar with the central portion of the adjacentspreader edge.

In order to enable the components to fit together tightly,

sockets are provided for the ends of the rib "spreaders.

Such a' socket may be 'formed by a bearing block.9

projecting from 'a side face of the central portion of a rib spreaderand having an edge spaced from the stringer strip 2. Such block may besecured to the rib spreader byany suitable means such as nails, screws,rivets or adhesrve. Each block has edges facing the stringer element 2which are shaped for abutment by the inner edges 10 of the rib spreaders4 of adjacent components'and together form-a peaked edge. If suchspreader edges 19 are planar throughout their entire length,-such peakededge of the .block'9 will have inclined'surfaces- 11 having an includedangle of 180 minus twice the angle'between the radial stringer planes orbetween the axes of pivots 5. Thus inthe particular example given, theangle between edges ill will be 189" minus twice 15 -or 30, making thetotal included obtuse-angle lSO".

In order to assemble the stringer components in side- 'by-siderelationshipas'shown in FIGURES 3, 9'and 10,

the pivots 5 of adjacentcomponents mustbe offset length;

wise equal to the thickness of the spreaders in order to enable suchspreaders to be disposed in face-to-face overlapping relationship, asshown in FIGURE 9. if the pivots 5 were spaced equidistantlyalong allthe comstringers moving r'elativelydengthwise so that theshelter wouldtend to become narrower and finally to collapse.

Relative endwise shifting of adjacent stringercomponents is prevented byproviding twoditierent types of compo- FIGURE 1.

In FIGURE 1, the two difierent types of components are designated A andB. In both of such components, the distances between adjacent pivots 5along the lengths of the stringers is unequal according to a pattern.Thus the spacing between the rib spreaders in one bay will be greaterthan the spreader spacing in the adjacent bays along the length of aparticular component by an amount equal to twice the thickness of aspreader. The spacing of the pivots 5 will vary correspondingly. Thebearing blocks 9 will be located at the opposite ends of the longer baysand the shorter bays will not contain any bearing blocks 9.

When components are oriented in relationship to be assembled, narrowbays of one component will be placed in registry with wide bays of theadjacent component, as shown in FIGURE 1. Thus the components A eachhave one narrow bay and one wide bay, whereas the components B have twowide bays and a narrow bay between them. Such components are shown withtwo bays and three bays, respectively, only for purposes ofillustration, and such components could be made much longer such ascomponents A having four bays and components B having five bays, forexample. In every instance, however, the bays will alternate in widthalong the length of each component. At each end of each component it ispreferred that the stringer elements project at least a short distance"beyond the rib spreaders.

While stop means could be provided in each component so that any givenspreader could be swung in only one direction from its collapsedposition to its expanded position, and only in the opposite directionback again to the collapsed position, provision of such stop means isunnecessary and it is quite satisfactory for each spreader to berotatable without restraint about its pivot 5. In expanding thecomponents from collapsed position by swinging the rib spreaders, it isonly necessary to remember that such spreaders must be swung to disposethe bearing blocks 9 in the wider bays of the spreaders, as illustratedin FIGURE 1. Also, the components should be arranged so that the gapbetween the ends of adjacent components occurs in a narrow bay in eachinstance. Such selection of the gaps will insure that the gaps inadjacent lines of stringer units will be staggered as shown in FIGURE 1.

When the stringer components have been arranged on the ground with therib spreaders in expanded condition, in the relationship shown in FIGURE1, they can readily be assembled progressively to erect a shelter frame.If the stringer elements of the components extend over the full lengthof the shelter, no joint between components in alignment will berequired. If the components do not extend over the entire length of theshelter, however, as is the case of the shelter structure shown inFIGURE 1, the endwise adjacent components should be assembled into acontinuous unit lengthwise before it is assembled laterally with anadjacent component or components by movement transversely of its length.Thus, starting from the bottom of FIGURE 1, the first step will be toinsert the stringer connector component C between the two components Aand B, so that the stringers of all three components are in alignment.

Details of the stringer connector component are shown in FIGURE 14. Suchcomponent includes stringer strip elements 12 which are held in spacedparallel relationship by end filler blocks 13 and, if necessary, acentral filler block 14. Side plates 15 overlap the end portions of thestringer strips 12 and the side faces of the end filler blocks 13 so asto provide sockets 16 adjacent to opposite edges of the filler blocks13. The manner in which the end projections of the stringer strips 1 and2 fit in the sockets 16 of the stringer connector components is shown inFIGURE 15. These sockets may be of any desired length parallel to thestringer strip elements 12, and transversely of such elements are of across-sectional size and shape the same as the cross-sectional size andshape of the stringer strip elements 12, 1 and 2. The stringer elements12 may be of any length, but the aggregate length of each of suchstringer elements and the projections on opposite ends of a component Aor B should be equal to the width of a narrower bay of the stringer andrib spreader components.

When the components A and B in the lower row of components shown inFIGURE 1 have been joined by the adjacent end portions of the stringerstrips 1 and 2 being fitted in the sockets 16 of the interposed stringerconnector component C, and the components A and B of the next row ofcomponents have been similarly joined by the interposed stringerconnector C, such aligned and joined components are assembled laterallyby relative movement transversely of their lengths. By such movement,the adjacent ends of the rib spreaders will be placed in overlappingrelationship as shown in FIGURE 2, and the ends of the spreaders will bewedged into the sockets between the blocks 9 and the stringer components2 in the manner shown in FIGURES 9 and 10. By such assembly, the pivots5 of adjacent components and the radial planes of such components willof necessity be tilted at the angle of tilt for which the rib spreadersare designed which, in the present example, has been assumed to be 15.

Following lateral assembly of the two lower components as described, thenext row of aligned components shown at the top of FIGURE 1 will bejoined in end-toend relationship by insertion of the stringer connectorcomponent C between them. Such row or line of components will then beready for assembly laterally with the already assembled rows ofcomponents by movement transversely of its length until the ends of itsrib spreaders are wedged into the sockets provided, as described above.Additional components or rows of components may be assembled laterallyin similar fashion, each ne being tilted through the arc for which therib spreaders were designed until an arcuate frame of the desiredperipheral extent has been formed. Usually, it is preferred that theextent of such are be approximately so as to form a semi-circular frame.A frame of such arcuate extent would require thirteen frames assembledin such lateral relationship where the radial angles between adjacentframes were 15 in order to complete it.

In order to provide additional head room in a shelter having asemi-circular vaulted roof, it may be desirable to provide vertical sidewalls at each side of the roof frame. Such vertical side walls can be ofany desired height and, as shown in FIGURES 3, 5 and 11, can befabricated from the same type of stringer components described above. Toform such a planar frame section, it is only necessary to assemble thecomponents in a different fashion, namely to reverse alternate rows ofcomponents side-for-side. Thus, instead of all the inclined spreaderedges 6 being at the same side of the frame, the arrangement of suchedegs will alternate with the straight edges 10.

As shown best in FIGURE 11, the tip of the spreader 4 shown at the topof this figure may be considered to be the center spreader 4 shown inFIGURE 10. The top stringer shown in FIGURE 11 would then be the bottomstringer of FIGURE 10. Instead of the next lower row of components beingarranged with their inclined edges 6 facing to the right, such row ofcomponents will be reversed side-for-side so that such inclined edgesface to the left while the planar edges 10 face to the right. Because ofthis arrangement, the planar edges 16, instead of the chamfered corners7, will abut the stringer strip 2, while such chamfered corners of thespreaders will abut the blocks 9. Similarly, the planar edges 10 of thespreaders of the components next to the top in FIGURE 11 will abut thestringer strips 2 of the reversed row of components and the chamferedcorner surfaces 7 at the bottom of the spreaders will abut the blocks 9of the reversed row of components.

comp orient.

The nextlower row of components will not be reversed, but the inclinedsurfaces'o of their spreaders Will face to the right and the planarsurfaces of such spreaders will face to the left. Again, however, 'theplanar surfaces of the spreaders in the nextto the bottom row ofcomponents will abut the stringer elements 2 of the lower row ratherthan the blocks 9, and the planar edges 10 of the upper ends of thespreaders of 'the lower row of components will abut the stringer stripsZof the reversed row of components next to the bottom. If the planar'Wall is to be continued downward, the next lower row of components alsowould be reversed so that their planar edges would face to the right andtheir inclined edges would face to the left. In this fashion, the wallwidth maybe continued to any desired extent by simply reversingside-for-side'the alternate rows of components.

When the vertical portion of the side wall has been bulit to the heightdesired, the lowermost row of components may be base componentsdiffering from the stringer components A and B described above. Suchbase components D arejshown in FIGURES 3, 4' and 5. Such base componentsinclude a sill element 17 on which the frame rests, and spreaders 18 aremounted stationarily on the sill 17. 'The lower portions of thespreaders may be of any convenient'height and, at -a location spacedupwardlyfrom the sill 17, will have attached to them blocks9dto fit ribspreaders 4' of the next higher The block 9 in each instance will belocated adjacent to the inner edge of the spreader 18 and a baseboard 19will extend alongside and'he secured to the outer edges of thespreaderslti. Such baseboard preferably is of a 'width to extend fromthe sill 17 upward to 'a location above the blocks a secured to suchspreaders. The spacing between such baseboard and the blocks 9 will beproper to accommodate the tips of the rib spreaders pro- ?ject'ingdownwardly from the component next-above the base'component. Also, theportion of spreader ls above 'the block 9 projecting from it will, ineach instance, be

tapered upwardly and of a lengthcorresponding to onehalf'of the'ribspreaders 10 of the other components.

Consequently, the components above the base component may be assembledto provide agvertical frame portion of greater or lesser Width above thebase component or such upper components can be assembled into arcuateshape immediately above the'base unit.

Whilethe components have been described as being assembled withrel-ation'to each other in a general way either to form a frame ofarcuate cross section. or of.

partially straight and partially arcuate cross section, ac-

- tually, in erecting a shelter frame, the components normally would beassembled progressively from opposite base units and would be joined atthe middle, or the stringer components couldbe assembled starting in theV middle of the arch and progressing toward the sides. ternatively,sections of the frame could be constructed and then such sections couldbe assembled. The components could even be assembled so that the convexside of the frame would be downward, and the resulting frame issufiiciently light and strong that, after it has been completed, it canbe inverted into standing upwardly convex condition.

By whatever procedure the frame or frame sections are fabricated, it isdesirable to secure the stringer components-in their assembledrelationship. Conveniently, the "assembled components can bebound-together by ties 20 illustrated in FIGURES 4 and 5 as light rodsor wires.

' Opposite ends. of these ties will be secured to the opposite sides ofthe shelter or shelter section constructed and will be drawn tight byturning turnbuckles 21. 'A convenient anchor for 'such ties may be-ahook 22 on one end of the turnbuckle 21 which is engaged'in an eye 23anchored-in the 'sill 17015 a base component.

As shown in. FIGURE 5, these tie members can extend upward over theinner side of thevertical wall portion and then as desired.

will pass between the stringer strips 1 and 2 and bear against the innerstringer stripsl throughout the arched portion of the shelter frame.Tightening of the turnbuckles 21 will therefore "draw "all the spreadersof the stringer components into closely'fitting relationship with thestringer strips and blocks forming the sockets in which they engage.

If the shelter is erected in sections, such a shelter conveniently canbe constructed in two halves, in which case the tie members 29 for theopposite sections could be anchored to adjacent stringer elementsapproximately at the center of the shelters arch. When the two sectionsof the shelter are assembled, the projecting ends of the rib spreaders 4would be fitted with the stringer strips and blocks in the mannerpreviously described and as shown in FIGURE 6. The stringer strips ofthe edge components of the sections can then be connected at intervalsby turnbuckle tie members 24, and such turnbuckles can be tightened todraw the two sections into snugly fitting relationship and to hold themin such position.

After theframe has been erected in the manner described, its assembledand overlapping rib spreaders will be stronger than a laminated beam ofsimilar proportions. The ends of the spreaders are not pierced by holesand take nearly al ltheir load in compression so that there is virtuallyno tendency of the wooden rib spreaders to split. Also, there are nostress concentration points produced by reliance upon clips or otherfastening devices. To fabricate laminated beams, the wood must be bent,whereas the elements of the components in the frame of the presentinvention are all made of straight wood.

pieces or pieces cut to shape. Even the cut pieces do not have weaksections running parallel to the grain.

The frarne has the further advantage which a laminated beam or arch doesnot have of being able to be knocked down readily for storage byseparating all the components by disconnecting the turnbuckle connectors24 and storing the separated sections without disassembling them.

The frame in erected condition canbe covered by a skin 25 which may becomposed of stiff or limp material In FIGURE '5, the skin is made oflimp sheet material, the edges of' which can be anchored to the basecomponent alongside the baseboard 19; For

i this purpose, a strip 26, having in its outer side a longitudinalgroove, is located alongside the baseboard in faceto-face relationshipwith it. The limp sheet material may be secured in such groove by afurther strip 27 which has a tongue or rib 23 seated in the groove. Thetwo strips are secured together by bolts 39 including wing nuts tofacilitate tightening them. Marginal strip assemblies secured toopposite edges of the skin 25 can be drawn toward the sills17 to tensionthe skin by helical tension springs 31 interconnecting the stripassemblies and the sill at intervals. Such springs will also urge thestrip 26 into contact with the baseboard -19.

in FIGURES 7 and 8, a stiff sectional typeof skin is illustrated,composed of corrugated strips 32 of a width, to span from one componentto thenext component. 7

Preferably, the opposite edges of each strip-overlap com- 'plet-ely thestringer elements behind them, and the edge portionsof adjacent stripstherefore overlap a distance equal to the width of a stringer element.Such sheet material, while being designated as stiff, may be ofcorrugated aluminum, for example, of sufiiciently thin In either case,the skin section strips 32 can be supported from the outer stringerstrips by hanger hooks 33 having one end portion to engage over astringer element and an outer upwardly opening portion into which thelower edge of a strip can fit. In order to provide Waterproof joints,such skin section strips can be arranged in shingled relationship sothat the upper edge of each skin strip lies behind and above the loweredge of the next higher skin strip. As shown in FIGURE 8, the inner hookportion of the hanger hooks can be of a width to fit over both astringer strip and the upper edge of a skin strip 32 and clamp theseelements tightly together. When the lower edge of the next higher skinstrip has been engaged in the upwardly opening hooks of the hangers,such skin strips will hold the hangers down in engagement with thestringer strips which the hanger hooks engage. A suitable cap strip maybe provided of double the width of skin strips 3-2 and can be slidendwise to engage its opposite edges with the hanger hooks, which willkeep the hanger hooks engaged by it positively spaced.

While the stringer components of the shelter frame described above haveincluded rib spreaders assembled with only a single stringer, it isquite feasible to combine rib spreaders with two or more stringers ifdesired. It is preferred to have more stringer members spaced closertogether Where it is expected that the shelter will be subjected togreater loads. In the components shown in FIGURES 16 to #20, inclusive,the rib spreaders are pivoted to and interconnect a plurality ofstringers. While each of the components illustrated includes only twostringers, a greater number of parallel stringers could be connected insimilar fashion. Thus the rib spreaders 34- are connected by pivots 35to parallel stringers including stringer strips 36 at one side of therib spreaders and 37 at the opposite side of the rib spreaders.Moreover, to increase the strength further, it will be evident that therib spreaders 34 could be made shorter and located closer together ifdesired.

Between the rib spreaders 34, it is preferred that the stringer stripsbe secured together and spaced apart positively by filler blocks 38secured between the stringer strips. In the expanded condition shown inFIGURE 16, and in the collapsed condition of FIGURE 17, the ribspreaders and the stringers will remain parallel because the pivots 35form of these members a parallelogram. In fully expanded condition therib spreaders 34 will be disposed perpendicular to the stringers 36, 37,but as the stringers are moved closer together, in the process of thecomponents being collapsed, the rib spreaders will be swung towardparallelism with the stringers but cannot be swung quite far enough toreach precise parallelism. The width of the stringer strips 36, 37governs the closeness of the approach of the rib spreaders toparallelism with the stringers as indicated in FIGURE 17. The ribspreaders in collapsed condition of the components will, however, benearly enough parallel to the stringers so that the components can bestored easily.

The expanded components can be assembled as shown in FIGURES 18, 19 and20 in a fashion similar to the procedure for assembling the componentsdescribed previously. Blocks 39 will be secured to the appropriate sideof each rib spreader to be engaged by the ends of spreaders of adjacentcomponents. Since each rib spreader is pivoted to a plurality ofstringers, such spreaders cannot be swung side-for-side about a pivotrelative to a particular stringer. Consequently, it is necessary for theblocks 39 to be attached to a particular side of each spreader so that,on adjacent spreaders, the blocks will project from sides facing eachother. The spreaders will be secured to the stringers at locations suchthat adjacent spreaders of one component will fit inside adjacentspreaders of the next component as shown in FIGURE 18. When thusassembled, the portions of the spreaders projecting in cantileverfashion beyond the stringers will overlap similarly projecting portionsof spreaders of adjacent components.

Components incorporating a plurality of stringers can have spreadersformed to enable a frame of generally arcuate character or a planarframe to be formed. The end portion of each spreader includes aninclined edge 46 and if such inclined edges are disposed all at the sameside of the frame, the resulting frame will have a generally arcuatecontour, as shown in the upper portion of FIGURE 19. If, however,alternate components are reversed side-for-side before being assembled,the resulting assembly will be planar as shown in the lower portion ofFIGURE 19 and in FIGURE 20. As in the type of shelter describedpreviously, the components may be arranged to form a planar frame of anydesired height integrated with a generally arcuate frame portion. Whenthe components have been assembled as shown in FIG- URES 18 and 19, theycan be secured in such erected condition by binding them together withtie members as described in connection with FIGURES 4 and 5. Also, ashelter frame thus constructed can be covered with a skin of either limpor stilf sheet material, using the construction and following theprocedure described in connection with FIGURES 4, 5, 7 and 8.

While the components described above can be collapsed laterally intocompact form for storage purposes in the manner described, it may bedesired to enable the components to be stored in a relatively shortspace. Instead of the stringers being formed of continuous ele ments,therefore, such stringers can be formed of comparatively short sectionswhich can be folded into overlapping relationship. One type of foldablecomponent structure is shown in FIGURES 21 to 26, inclusive, asincluding stringer sections 41 connected by hinge means at locationsbetween rib spreaders 42 swingably secured to the stringers by pivots43; The hinge means utilized in this structure includes a filler block44, which is connected to the adjacent ends of adjacent stringersections 41 by pivot bolts 45, respectively. As shown best in FIGURE 25,the corners of the stringer elements at one side of the hinged jointhave chamfered corners 46. The space between such corners will enablethe stringer sections 4 1 to be folded from the solid line position ofFIGURE 26 toward the broken line position without interference. Eventhough the pivots 45' are spaced from each other more than the width ofa stringer 41, the stringer sections can be folded into contiguousedge-to-edge engagement by swinging the filler block 44 into the brokenline positionof FIGURE 26 which serves as a connecting link.

In collapsing a component of the type shown in FIG- URES 21 to 26inclusive, the first step is to swing the rib spreaders 42 intopositions parallel to the respective stringer sections in which they aremounted, as shown in FIG- URE 21. The next step is for the sections ofthe components to be folded alternately in opposite directions about thepivots 45 toward the relationship shown in FIGURE 22. The folding isthen continued until the sections are in side-by-side contiguousabutment, as illustrated in FIG- URE 23. During such folding of thesections, the hinge linkage will move from the solid line position ofFIGURE 26 to the broken line position. By reverse movement of thesections 41, they can again be stretched from the relationship of FIGURE23 through the relationship of FIG URE 22 into the aligned relationshipof FIGURE 21.

An alternate type of hinge means for connecting the adjacent ends ofadjacent stringer sections is shown in FIG- URES 27 to 31. While, inthese figures, only two stringer sections 41 are shown, it will beevident that any number of sections can be connected end-to-end simplyby reversing the application of the hinge means at the opposite ends ofeach section. The rib spreaders 42 are mounted swingably between theelements of the stringer sections 41 by pivots 43 in the mannerdescribed in connection with aligned position into folded position. 'thestringer'sections are unfolded from the position of "FIGURE 28 to -thatof FIGURE 27, relative swinging -movement-of the sections will beinterrupted when they ly'to the filler blocks 47 by screws shown in fulllines in FIGURES 29 and-3l, and in broken lines in FIGURE 30.

The axis of the hinge pintle, as shown best in FIGURE 30, is disposed nthe plane of the joint between the two stringer sections 41, and isdisposed alongside such stringer sections so'that,'in the foldedcondition shown in FIG- URE -ZS, and in broken lines in FIGURE 30, thesections will lie close alongside each other but their ends will notinterfere with each other in swinging from extended Conversely, whenreachalignment by abutment of the-adjacent ends of thestringer-sections. a

-As-has been explained above, the components described .can be assembledto form either an arcuate frame portion or a; planar frame portion.

In some instances, it may be desirable to provide stringer and ribspreader components which can be employed in assembling frames ofarcuate *shape, but of different curvatures. Stringer and rib spreadercomponents of this typeare-shownin FIGURES 32 corners53 maybe-identicalv with the edges 6 and charn :tered corners 7 of thespreaders shown in FIGURES 9 to 13.

.. A.block.54.projecting from...the side of each spreader 50. adjacentto its edge remote from theinclined surfaces 52 is comparable to theblock 9 of each spreader 4 in the .componentshownin FIGURES 9 to 13. Theends of the spreaders Stiofadjacent components can be overlapped andengaged with the blocks 54' and stringer strips 49 inthemanner shown inFIGURE 34 which is directly comparable to the-engagement of thespreaders of adjacent componentsas shownin FIGURE 10. Progressiveassembly of such components, with. the inclined edges 52 of all.components being .on corresponding sides, will produce. an arcuateframe. as shownin FIGURE 35'which is of the same curvature as the frameshown in FIGURE 3,

that is, the angle between the pivots or stringer planes of adjacentcomponents is 15 asgindicated in FIGURE 34 and FIGURE 10.

The same components of FIGURES 32 and 33 alternatively can be assembledto form an arcuate framehaving a difierent .degree of curvature which,for purposes of il-' lustration, has .been selected asoflesser curvaturethan the frame of FIGURE 35. In such alternate frame, the angle betweenthe pivots or stringer planes of adjacent compo-. nents has beenselected as as'shown in FIGURE 36 instead of as indicated inFIGURE 34. Aframe having 10 angles between the pivots of adjacent compo- ;nents maybe used to form an arched roof frame, for example, as illustrated inFIGURE 37 A frame of this type can: be assembled from the componentsshown in FIGURES 32 and 33 simply by swinging all of therib.

spreaders end-for-end relative to the stringer elements 48 and 49, asindicated by the arrow in FIGURE 32 from the position of that figure tothe position shown in FI 'URE 33. Such reversalwill place blocks 55,.projecting from thesides of the rib spreaders 50 opposite blocks 54, atopposite'sides of the wider bays of the components and facing each otherin lieu of blocks 54.

Whenadjacent components are now assembled by lateral movement, the ribspreaders. willbe tilted oppositely because the blocks -.are locatedadjacent to the edges 52 12 ofthe'spreaders instead of remote from them.The-curvature shown in FIGURES '3d and 37- results from the edges *56 ofthe rib spreaders dtitnot bei g linear or planaras are the edgesiti ofthe ribspreaders shown in FIGURES 12 and 13, but such edges 56also areinclined with respect to planes perpendicular'to the pivots 51. Insteadof being inclined relative to such planes by an angle of 7 /2 as aretheedges 52, the edgesi-are inclined relative to such planes by-anangleof only 5. The chamfered corners 57 at theends of the edges areinclinedrelative to the edges as also. at an angle of 5.

It will be evident that in designingthe peaked edges of blocks S t-and55,. consideration must be given to the angles of both chamfered corners56 and 57. Since, in both. instances, the tips of the ribspreadersmust'fit betweenan inner surface of astringerstrip and theadjacent -edge of ablockfid or .55, the. peakangles .of such blocks .54and'SS will be the same. .Theangle between each side of the blocks peakand the inner surface of the adjacent stringer stripwill be 25 takinginto account the angle of both chamfered corners 53 and 57.Consequently, the obtuserpeakangle of each block 54. and Y55 will be130.

In the stringer and rib. spreader components described above, locationof adjacent components relative to each other depended upon the ends ofthespreaders being :pushed-firmly into engagement between astringerelement 2 and a bearing block9, as shown in FIGURES 9 and 10, forexample. The tipsof the spreadersare tapered ;and depending upon themoisture content of the wood of V which the components are made theelements of each cornponent will shrink or swell to;some extent. Also,some persons might force the end ofa stringer into its socket If thespreader ends with greater pressure than another. are not locatedreasonably accuratelyrelative to their sockets, one stringer end mayproject beyond the peak .of a bearing block 9. In that event, the end ofthe other spreader engaging such bearing block may be inserted into itssocket an insufficient distance and'so as to be looser than desired.Also, if the end of one spreader is forced into its socket with greaterforce than desirable, the bearing block and stringer elements may besubjected to exc-essive force.

In order to insure proper location of the ends of the spreader membersrelative to their sockets in adjacent stringer components, the. ends ofthe spreaders can be provided with stop shoulders limiting movement ofthe spreader tips into their sockets. Such a construction is shownin'FIGU'RE 38 in which the spreaders 58 are mounted on pivots 5 betweenthe stringer strips '1' and 2. "these stringer strips are like thoseshown in FIGURES 9 to '13, inclusive, and the'bearing blocks 9 are ofsimilar character. The central portions of the rib spreaders 53 aresimilar to the central portions of the rib spreaders? shown in the samefigures, and one edge 59 of each'of such spreaders is planar. Theopposite edge 60 of each rib spreader is inclined but the taper betweenedges 59 and Gtlwill be less than the taper between edges 6 audit of thespreaders 4 for a given angle between the central radial planes ofadjacent stringers when the components are assembled.

Thereduction in angle between'the opposite edges 59 andt) of thespreaders 58 will provide. sufiicient stock a 7 width atthe tips of thespreaders to form a shoulder .61 adjacent to the chamfered corners 62 ofthe spreader tips. Such shoulders will be spaced from the extreme end ofthe spreaders a distance approximately equal to one-half the widthof'the stringer elements 2. Consequently, when thetips of the spreadersare pushed into ---their'sockets, their seating movement will be limitedby element 2. When the spreader tips are thus disposed, theirextreme'innerlendswill not project intotheir sockets beabutment of theshoulders fil 'with the sides of the stringer.

In the stringer and rib spreader components described above, thespreader pivots are spaced unequally along the stringers so as toprovide alternate wide bays and narrow bays. Such pivot spacing enablesthe spreader ends of adjacent components to be interfitted inoverlapping relationship as illustrated in FIGURES l and 2. For suchconstruction, however, as has been explained previously, it is necessaryto provide two different types of components designated in FIGURES 1 and2 as components A and components B. It is possible, however, to employthe principles of the present invention in a construction fabricatedfrom components all of the same type. Such a construction is illustratedin FIGURES 39 to 42, inclus1ve.

In FIGURE 39, components D are shown arranged in side-by-siderelationship ready for assembling by relative movement transversely oftheir length. It will be evident that the rib spreaders 63 of thesecomponents are arranged to be interfitted by such movement so that theadjacent ends of the spreaders of adjacent components will be disposedin overlapping relationship even though the pivots 5 are spacedequidistantly along the stringers I, 2. While each of the components Dis shown as having only two stringer bays, it will be evident that eachcomponent may have as many bays as desired, and the stringers can becontinuous or can be foldable like the constructions described above.

While the shelter frame of the type shown in FIGURE 2 requires threedifferent types of components to be interfitted, a comparable framestructure can be formed of the single type of component B shown inFIGURE 39, and such components can be joined end-to-end to form ashelter of any desired length by the simple expedient of positioning thecomponents in adjacent stringer rows alternately end-for-end. While thespreaders 63 are all swung in the same direction relative to thestringer for each component, the blocks of alternate components willface in opposite directions as shown in FIGURE 39. Moreover, the lengthof the stringer section projecting beyond the last spreader pivot at oneend of the component will differ from the projection of the stringerbeyond the spreader pivot at the other end of such component by thethickness of a bearing block 64 or a spreader 63.

When the adjacent stringer and rib spreader components are reversedend-for-end and the ends of adjacent components are in registrytransversely of the length of the stringers, the spreaders of adjacentcomponents are disposed in relationship offset sufficiently so thattheir adjacent ends can be assembled in side-by-side overlappingrelationship. As the components are moved toward each other transverselyof their lengths, therefore, the adjacent spreader ends will pass eachother and the tips of the spreaders will engage in their respectivesockets between the str-inger element 42 and a bearing block 64-attached to the side of a spreader. Adjacent ends of stringers inlongitudinally aligned components can be connected together to form acontinuous stringer in any suitable fashion such as by placing a fillerblock 65 bridging between the adjacent ends of the stringer elements Iand 2 in adjacent components and securing such block and the stringerends together by bolts 66 as shown in FIGURE 42.

If the spreaders and bearing blocks of the components D, shown in FIGURE39, were constructed like the rib spreaders 4 and bearing blocks 9 ofthe components shown in FIGURES 9 to 13, it would be possible for thecomponents to be moved relatively endwise to move the overlapping endsof the spreaders apart. Such movement is prevented where components ofthe types designated A and B are interfitted as shown in FIGURE 1. Inthe rrangernent of FIGURE 39, however, all of the spreaders of onecomponent are at corresponding sides of the spreaders of adjacentcomponents.

In order to prevent such separating movement of overlapping spreaderends, the spreader tips and their sockets are formed for interlockingengagement. The suitable interlocking construction is shown in FIGURES40 and 41. The inclined sides of these spreaders have the same shape asthe spreaders shown in FIGURE 38, namely an inclined edge 60 which isinclined at an angle less than the edges 6 of the spreaders shown inFIGURES 9 to 13. Such edges, then, have a shoulder 61 spaced from theirextreme ends a distance equal to half the width of a stringer element 2and between the shoulder and the extreme end of the spreader is thechamfered corner 62. The opposite edge 59 is planar throughout itslength, although the width of such surface is not uniform throughout itslength.

The bearing block 64 projecting from one face of a spreader 63 has itspeaked edge stepped so as to form a ledge 65 adjacent to the spreaderand a ridge 66 spaced from the spreader defining a groove between theridge 66 and the adjacent side of the spreader. The bottom of the grooveformed by the ledge is spaced from the stringer strip 2 a distance equalto the spacing of the peaked edge of bearing block 9 from the stringerstrip 2 in the components shown in FIGURES 9 to 13 and 38. The ridge 66projects beyond the ledge 65 by any desired reasonable amount.

In order to enable the tips of spreads 63 to fit into the socketsbetween the bearing blocks 64 and the stringer strip 2, it is necessaryto form in the tip end portion of each spreader a recess 67 of a depthto accommodate the ridge 66. Also, the extent of such recesstransversely of the spreader must in each instance be at least equal tothe thickness of a ridge 66. As the end portions of the spreaders 63 aremoved transversely of the lengths of the stringers toward their socketsas indicated by the broken arrows in FIGURE 40, the projections 63 ofthe spreader ends will lodge in the grooves 65 while the ridges 66 wedgeinto the recesses 67, as shown in FIGURE 41. Such engagement of theprojections 68 in the grooves will prevent the ends of the spreadersfitted into their sockets from being moved past the ridges 66 and,consequently, the overlapping end portions of the spreaders will be heldagainst separation in a direction transversely of the lengths of thespreaders and parallel to the lengths of the stringers.

After the components D have been assembled in the manner described, theymay be secured together into sections of a shelter or into a completeshelter frame in the manner described in connection with FIGURES 4 and5, and then the frame can be covered with a skin as discussed withrelation to FIGURES 4, 5, 7 and 8.

I claim as my invention:

1. A demountable shelter component comprising elongated stringerelement, an elongated rib spreader, having its length extendingtransversely of the length of said stringer element, pivot meansmounting said rib spreader at one side of said stringer element forswinging between an expanded position disposed transversely of saidstringer element and a collapsed position disposed substantiallyparallel to said stringer element, and a block secured to one of thesides of said rib spreader and spaced from said stringer element in adirection transversely of said rib spreader, forming between said blockand said stringer element a socket for reception of the end portion of arib spreader of another similar shelter component.

2. A demountable shelter component comprising an elongated stringerhaving its length divided into a plurality of elongated sections andhaving hinge means interconnecting said sections for relative foldingfrom substantially end to end aligned relationship into overlappingrelationship to reduce the overall length of said stringer for storage,an elongated rib spreader for each stringer section, and pivot meanslocated between the ends of stringer sections, respectively, andmounting each rib spreader on its stringer section for swinging betweenan expanded position projecting from its stringer section transverselyof the length of such stringer section and a collapsed positionsdisposed transversely of said stringer and collapsed positions swungtoward said stringer, and socket means forming a notch between saidstringer and one of the sides of each of said rib spreaders adjacent tosaid stringer for engagement with a rib spreader of another sheltercomponent.

4. A dernountable shelter frame structure comprising a plurality ofstringer components each including a stringer, said stringer componentsbeing assembled with their stringers in parallel relationship, a firstone of said stringer components having a rib spreader pivotally mountedbetween its ends on a stringer of its stringer component for movementbetween a position extending transversely of such stringer and acollapsed position generally parallel to such stringer, and socket meanson one side of said first stringer component rib spreader spaced fromthe ends of such rib spreader and engaging the end portions of adjacentstringer component spreaders in relationship lengthwise overlapping saidfirst stringer component .rib spreader.

5; 'A demountable shelter component comprising a.

stringer, a plurality of rib spreaders, a plurality of pivotmeausdisposed in spaced relationship along said stringer and mountingthe central portions of said rib Spreaders, respectively, for swingingof said rib Spreaders relative to said stringer between expandedpositions disposed transversely of said stringer with their oppositefree end portions extending a substantial distance beyond said stringerfor engagement with adjacent stringers, respectively, andcollapsedpositions swung toward said stringer, and each of said ribspreaders having socket means spaced from its ends of a shapecomplemental to the end portions ,of said rib spreaders for receiving anend portion of a rib spreader of a similar adjacent component.

6. A demountable shelter component comprising a stringer includingspaced parallel inner and outer stringer "strips, a plurality of ribspreaders disposed between said stringer strips, a plurality of pivotmeans disposed in spaced relationship along and extending between saidstringer strips and mounting the central portions of said rib spreaders,respectively, for swinging of said rib Spreaders between expandedpositions disposed transverse ly of said stringer with their oppositefree end portions extending a substantial distance beyond said stringerfor engagement with adjacent stringers, respectively, and collapsedpositions swung substantially parallel to said .stringer, and each ofsaid rib spreaders having socket means spaced from its ends of a shapecomplemental to the end portions ofsaid rib spreaders for receiving anend portion of a rib spreader of a similar adjacent component.

7. A demountable shelter frame structure comprising a plurality ofspaced, substantially arcuate, substantially parallel upright frames,each of said frames being composed of rib Spreaders assembled withportions of adjacent spreaders disposed in lengthwise overlappingrelationship, and a plurality of elongated substantially horizontalstringer elements disposed in parallel arrangement spaced lengthwise ofsaid frames, each of said stringer elements having a surface disposedsubstantially tangential to one of said arcuate frames bearing on anedge portion of a first rib spreader in such frame between the ends ofsuch first rib spreader, and said stringer element having a surfacedisposed substantially perpendicular to said first rib spreader abuttinga surface of a second rib spreader in the same frame which surface isdisposed transversely of the length of, said second rib spreaden'forpreventing movement of such stringer element lerigt Wise of such'frarne.

8. The demountable shelter frame structure defined in claim 7, in whichthe stringer element engaging the frame is disposed outwardly of suchframe, the inner surface of such stringer element engages the outer edgeof the first rib spreader and an end portion of the second ribspreaderhas a notch adjacent to its outeredge forming a shoulder constitutingthe surface of the second rib spreader abutted by the stringer element.

References Cited in the file 0:15 this patent UNITED STATES PATENTS19,689 Dinsmoor Mar. 23, 1858 39,721 Cross Sept. 1, 1863 451,572 RankinMay 5,1891 841,058 Sherlock Jan. 8, 1907 1,450,129 Batty Mar. 27, 19231,704,275 Badel Mar. 5, 1929 1,721,198 Athey July 16, 1929, 1,843,312Arnes Feb. 2, 1932 1,985,599 Gates Dec. 25, 1934 2,013,820 Wilson Sept.10, 1935 2,065,256 Wilson Dec. 22, 1936 2,197,065 'Bland Apr; 16, 19402,250,175 Blaski July 22, 1941 2,250,911 Hoeckendorf July 29, 19412,289,832 Flesner July 14, 1942 2,475,433 McLaughlin July 5, 19492,534,852 Butts Dec. 19, 1950 2,652,599 Rodda Sept. 22, 1953 FOREIGNPATENTS 492,722 France 1919 176,966 Austria 1953 L11,715V 1926 GermanyMay 30,

1. A DEMOUNTABLE SHELTER COMPONENT COMPRISING ELONGATED STRINGERELEMENT, AN ELONGATED RIB SPREADER, HAVING ITS LENGTH EXTENDINGTRANSVERSELY OF THE LENGTH OF SAID STRINGER ELEMENT, PIVOT MEANSMOUNTING SAID RIB SPREADER AT ONE SIDE OF SAID STRINGER ELEMENT FORSWINGING BETWEEN AN EXPANDED POSITION DISPOSED TRANSVERSELY OF SAIDSTRINGER ELEMENT AND A COLLAPSED POSITION DISPOSED SUBSTANTIALLYPARALLEL TO SAID STRINGER ELEMENT, AND A BLOCK SECURED TO ONE OF THESIDES OF SAID RIB SPREADER AND SPACED FROM SAID STRINGER ELEMENT IN ADIRECTION TRANSVERSELY OF SAID RIB SPREADER, FORMING BETWEEN SAID BLOCKAND SAID STRINGER ELEMENT A SOCKET FOR RECEPTION OF THE END PORTION OF ARIB SPREADER OF ANOTHER SIMILAR SHELTER COMPONENT.